1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
4  * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
5  */
6 
7 /*
8  * i.MX27 specific CPU detection code
9  */
10 
11 #include <linux/io.h>
12 #include <linux/of_address.h>
13 #include <linux/module.h>
14 
15 #include "hardware.h"
16 
17 static int mx27_cpu_rev = -1;
18 static int mx27_cpu_partnumber;
19 
20 #define SYS_CHIP_ID             0x00    /* The offset of CHIP ID register */
21 #define SYSCTRL_OFFSET		0x800	/* Offset from CCM base address */
22 
mx27_read_cpu_rev(void)23 static int mx27_read_cpu_rev(void)
24 {
25 	void __iomem *ccm_base;
26 	struct device_node *np;
27 	u32 val;
28 
29 	np = of_find_compatible_node(NULL, NULL, "fsl,imx27-ccm");
30 	ccm_base = of_iomap(np, 0);
31 	of_node_put(np);
32 	BUG_ON(!ccm_base);
33 	/*
34 	 * now we have access to the IO registers. As we need
35 	 * the silicon revision very early we read it here to
36 	 * avoid any further hooks
37 	*/
38 	val = imx_readl(ccm_base + SYSCTRL_OFFSET + SYS_CHIP_ID);
39 
40 	mx27_cpu_partnumber = (int)((val >> 12) & 0xFFFF);
41 
42 	switch (val >> 28) {
43 	case 0:
44 		return IMX_CHIP_REVISION_1_0;
45 	case 1:
46 		return IMX_CHIP_REVISION_2_0;
47 	case 2:
48 		return IMX_CHIP_REVISION_2_1;
49 	default:
50 		return IMX_CHIP_REVISION_UNKNOWN;
51 	}
52 }
53 
54 /*
55  * Returns:
56  *	the silicon revision of the cpu
57  *	-EINVAL - not a mx27
58  */
mx27_revision(void)59 int mx27_revision(void)
60 {
61 	if (mx27_cpu_rev == -1)
62 		mx27_cpu_rev = mx27_read_cpu_rev();
63 
64 	if (mx27_cpu_partnumber != 0x8821)
65 		return -EINVAL;
66 
67 	return mx27_cpu_rev;
68 }
69 EXPORT_SYMBOL(mx27_revision);
70